liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Phagocytosis and phagosome maturation are regulated by calcium in J774 macrophages interacting with un-opsonized prey
Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology . Linköping University, Faculty of Health Sciences.
2002 (English)In: Bioscience Reports, ISSN 0144-8463, Vol. 22, no 5-6, 529-540 p.Article in journal (Refereed) Published
Abstract [en]

Phagocytosis by neutrophils, macrophages, and other professional phagocytes requires rapid remodeling of actin. Early phagosomes are surrounded by a rim of F-actin that is disassembled during phagosomoal maturation. Breakdown of periphagosomal F-actin and phagolysosome fusion are calcium dependent processes in neutrophils interacting with serum-opsonized prey, but appears to be calcium independent in macrophages interacting with serum- or IgG-opsonized prey. In the present study, we found that calcium was necessary for phagocytosis, breakdown of periphagosomal F-actin, and phagosomal maturation in J774 macrophages interacting with unopsonized prey. We also observed that lipophosphoglycan (LPG) from Leishmania donovani promastigotes required calcium to exert its inhibitory effect on macrophage phagocytosis and periphagosomal F-actin breakdown. We conclude that calcium is essential for phagocytosis, depolymerization of periphagosomal F-actin, and phagosomal maturation in J774 macrophages interacting with unopsonized prey, as well as for proper functioning of LPG.

Place, publisher, year, edition, pages
2002. Vol. 22, no 5-6, 529-540 p.
Keyword [en]
Macrophage, phagocytosis, calcium, actin, phagosome maturation, lipophosphoglycan
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-13849DOI: 10.1023/A:1022025903688OAI: oai:DiVA.org:liu-13849DiVA: diva2:21860
Available from: 2006-05-23 Created: 2006-05-23 Last updated: 2013-09-18
In thesis
1. Leishmania donovani Lipophosphoglycan: Modulation of Macrophage and Dendritic Cell Function
Open this publication in new window or tab >>Leishmania donovani Lipophosphoglycan: Modulation of Macrophage and Dendritic Cell Function
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Leishmania donovani is a blood-borne tropicial parasite, which infects humans through bites by Phlebotomus sandflies. The parasite survives and multiplies inside macrophages in inner organs, and causes the deadly disease visceral leishmaniasis (Kala-Azar).

Macrophages and dendritic cells (DC) are professional antigen-presenting cells involved in the initiation of immune responses. Immature DC are present in all tissues where they internalise and process antigen, in response to which they migrate from tissue, into draining lymphoid organs, undergo maturation and present antigens to lymphocytes. Control measures for leishmaniasis include testing of new diagnostics and development of affordable and effective vaccines for humans.

Lipophosphoglycan (LPG) is the major surface component of Leishmania donovani promastigotes. LPG comprises a membrane-anchoring lysophosphatidylinositol part and an extracellular chain of disaccharide phosphates. These repetitions are crucial for parasite survival inside macrophages following phagocytosis. LPG has several specific effects on the host cell including inhibition of protein kinase C (PKC) activity, and inhibition of phagosomal maturation, a process requiring depolymerization of periphagosomal F-actin.

Confocal microscopy and image analysis were used to follow F-actin dynamics in single macrophages during phagocytosis of L. donovani promastigotes and LPG-coated particles. F-actin did not depolymerize, but instead progressively polymerized around phagosomes with LPG-containing prey. This correlated with reduced translocation of PKCα to the phagosome and blocked phagosomal maturation. LPG also inhibited cortical actin turnover, which could be the underlying cause of the reduced uptake of LPG-containing prey. Extracellular- and intracellular calcium was necessary for phagocytosis, periphagosomal F-actin breakdown and phagosomal maturation in macrophages interacting with unopsonized prey,and for the action of LPG.

We also studied F-actin turnover in macrophages overexpressing dominant-negative (DN) PKCα. DN PKCα macrophages showed increased amounts of cortical F-actin, decreased phagocytic capacity, inhibition of periphagosomal F-actin breakdown and defective phagosomal maturation. When DN PKCα macrophages interacted with LPG-containing prey, phagocytosis was almost completely blocked.

Moreover, we found that Leishmania promastigotes and particularly LPG inhibit DC maturation and detachment from distinct surfaces. Thus, LPG from Leishmania donovani could directly inhibit DC migration to lymphoid organs, antigen-presentation and development of immunity.

Place, publisher, year, edition, pages
Institutionen för molekylär och klinisk medicin, 2006
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 946
Series
Keyword
Lipophosphoglycan, Leishmania donovani, macrophage, actin, phagocytosis, PKC alpha, dendritic cell
National Category
Pathobiology
Identifiers
urn:nbn:se:liu:diva-6527 (URN)91-85497-84-3 (ISBN)
Public defence
2006-06-01, Linden, Campus US, Linköpings universitet, Linköping, 09:00 (English)
Opponent
Supervisors
Available from: 2006-05-23 Created: 2006-05-23 Last updated: 2009-06-05
2. Effects of lipophosphoglycan on macrophage actin dynamics
Open this publication in new window or tab >>Effects of lipophosphoglycan on macrophage actin dynamics
2002 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Leishmania donovani is a blood-borne tropicial parasite, which infects humans through bites by Phlebotomine sandflies. The parasite survives and multiplies inside macrophages in inner organs, and causes the deadly disease visceral leishmaniasis (Kala-Azar). Lipophosphoglycan (LPG) is the major surface component of Leishmania donovani promastigotes. LPG comprises a membrane-anchoring

lysophosphatidylinositol moiety and an extracellular chain of repeating disaccharide phosphates. The repeats are crucial for parasite survival inside macrophages following phagocytosis. LPG has several effects on the host cell including inhibition of protein kinase C (PKC) activity, and inhibition of phagosomal maturation, a process requiring depolymerization of periphagosomal F-actin. Confocal microscopy and image analysis was used to follow F-actin dynamics in single macrophages during phagocytosis of L. donovani promastigotes and LPG-coated particles. F-actin did not depolymerize, but instead progressively polymerized around phagosomes with LPG-containing prey. This directly correlated with reduced translocation of PKCα to the phagosome and blocked phagosomal maturation. It was also found that LPG inhibited cortical actin turnover, which may be the underlying cause of the reduced uptake of LPG-containing prey. Free calcium was necessary for phagocytosis, periphagosomal F-actin breakdown and phagosomal maturation in macrophages interacting with unopsonized prey. LPG required free calcium to exert its inhibitory effects on these processes. We also studied F -actin turnover in macrophages overexpressing dominant-negative (DN) PKCα. DN PKCα macrophages showed increased amounts of cortical F-actin, decreased phagocytic capacity, inhibition of periphagosomal F-actin breakdown and defective phagosomal maturation. When DN PKCa macrophages interacted with LPG-containing prey, phagocytosis was almost completely blocked.

Together, our results indicate that blockage of F-actin breakdown through inhibition of PKCa by LPG reduces phagocytosis and is instrumental for the inhibition of phagosomal maturation induced by L. donovani promastigotes.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2002. 42 p.
Series
Linköping Studies in Health Sciences. Thesis, ISSN 1100-6013 ; 58
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-26683 (URN)11250 (Local ID)91-7373-190-0 (ISBN)11250 (Archive number)11250 (OAI)
Presentation
2002-12-10, Hälsouniversitetet, Linköping, 10:15 (Swedish)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2013-09-18

Open Access in DiVA

No full text

Other links

Publisher's full textLink to Ph.D. Thesis

Authority records BETA

Tejle, KatarinaMagnusson, Karl-EricRasmusson, Birgitta

Search in DiVA

By author/editor
Tejle, KatarinaMagnusson, Karl-EricRasmusson, Birgitta
By organisation
Medical Microbiology Faculty of Health Sciences
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 148 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf